Both multiple motor and one or more vocal tics
have been present at some time during the illness, although not necessarily concurrently.
(A tic is a sudden, rapid, recurrent, nonrhythmic, stereotyped motor movement or
vocalization.)
The tics occur many times a day (usually in bouts) nearly every day or intermittently
throughout a period of more than 1 year, and during this period there was never a tic-free
period of more than 3 consecutive months.

The disturbance causes marked distress or significant impairment in social, occupational,
or other important areas of functioning.

The onset is before age 18 years.

The disturbance is not due to the direct physiological effects of a substance (e.g.,
stimulants) or a general medical condition (e.g., Huntington's disease or postviral
encephalitis). Source:
Criteria summarized from:
American Psychiatric Association. (1994). Diagnostic and statistical manual of mental
disorders, fourth edition. Washington, DC: American Psychiatric Association.